Controlled Particle Transport in a Human Airway Replica

by Rojas, Carlye Rimmele

Abstract (Summary)

ROJAS, CARLYE RIMMELE. Controlled Particle Transport in a Human Airway
Replica. (Under the direction of William L. Roberts).
The goal of this research is a proof-of-concept for targeted aerosol delivery and
validation of computational results. Sodium chloride particles, with a monodisperse
particle size of one micrometer are used to represent a drug aerosol in the experimental
validation of computational results. A complex oral airway, including a mouth, larynx,
pharynx, and trachea was constructed out of laser cured resin, using a three-dimensional
printing method. A symmetric three generation (G0 to G3) bifurcating bronchial airway
was constructed using the same process. Two-phase flow was conducted through these
models to yield particle transport results. The bulk air flow was 2 liters per minute, the
highest observed flow rate that will allow the flow to remain laminar throughout the
airway model. The flow rate of the particle seeded flow was maintained at 20 milliliters
per minute. The velocities of these two flow rates remain within an order of magnitude
of each other to inhibit vortices created by shear forces when the two flows were
introduced. A series of nozzles (constructed using SL) were used to control the particle
injection location. A one millimeter inner diameter seed nozzle is offset, from the center,
a given percent of the radius. There were five nozzles, with increasingly offset seed
tubes, 0% (centerline of axisymmetric nozzle), 20%, 40%, 60%, and 80%. The airway
model was attached to the nozzle so that the nozzle exit is in the same plane as the mouth
entrance. The nozzle was rotated so that the seed tube exit can be positioned at various
angles within the circular cross-section. By controlling the particle release position, the
deposition efficiency can be increased, dramatically, as compared to the uniform
injection of the drug. The results show the controlled particle release can determine
which branch or branches of the third generation bifurcating bronchial airway the
particles will exit. While numerous previous researchers have studied the deposition
effects of a uniform injection of aerosol particles in the human airways, the controlled
position of particle release is an original idea.